Expandable fusion device with integrated deployable retention spikes

ABSTRACT

Expandable fusion devices, systems, and methods. The expandable fusion device includes one or more integrated deployable retention spikes configured to resist expulsion of the device when installed in the intervertebral disc space. The implant may include upper and lower main endplates, an actuator assembly configured to cause an expansion in height of the upper and lower main endplates, and a sidecar assembly including a sidecar carrier, an upper carrier endplate engaged with an upper spike, and a lower carrier endplate engaged with a lower spike such that forward translation of the sidecar carrier pushes against the upper and lower carrier endplates, thereby deploying the upper and lower spikes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 17/540,381, filed on Dec. 2, 2021, which isincorporated by reference herein in its entirety for all purposes.

FIELD OF THE INVENTION

The present disclosure relates to surgical devices, and moreparticularly, to expandable fusion devices capable of being insertedbetween adjacent vertebrae to facilitate the fusion process andincluding integrated deployable retention spikes configured to preventexpulsion of the device.

BACKGROUND

Sagittal imbalance accompanied by one or more spinal pathologies isoften treated through a combination of direct and indirectdecompression. Indirect decompression may be achieved through theplacement of an intervertebral cage. The combination of osteotomy of theposterior elements, placement of cage(s), and subsequent compression ona pedicle screw/rod construct can be used to restore segmental lordosisto the operative level, thus restoring sagittal balance to the region.

The midline-sacrificing intradiscal osteotomy technique involvesosteotomy of the posterior elements and ligamentum flavum, and opening awide access to underlying dural sac and the disc space. Osteotomes maybe used to remove posterior osteophytes and the disc en-bloc. Theanterior longitudinal ligament (ALL) is released via spreader or bluntdissection, and bi-lateral expandable cages are placed on a posteriorlumbar interbody fusion (PLIF) trajectory. Rods are reduced into screwsplaced prior to the osteotomy, and the screws are compressed. As thescrews are brought closer together, the vertebral bodies rock about thefulcrum created by the interbody spacers, and segmental lordosis isincreased, yielding the desired correction.

Due to the corrective nature of the procedure, a hyperlordoticexpandable cage with a high degree of adjustability is needed. A highlordotic profile cage may have an increased risk of anterior expulsiondue to increased forces in the axial plane. Due to the resection of theanterior longitudinal ligament, the natural barrier that would preventanterior expulsion out of the disc space is no longer there. As such,there exists a need for an expandable fusion device that includes one ormore anti-expulsion features.

SUMMARY

To meet this and other needs, and in view of its purposes, the presentapplication provides devices, systems, and methods for installing andexpanding an interbody implant and deploying integrated retentionspikes. The expandable implants may include one or more integratedretention spikes configured to deploy from the implant body to resistexpulsion of the implant from the disc space. In addition, theexpandable interbody implants may be configured to communicate implantinformation with a robotic and/or navigation system. For example,position and orientation of the implant may be communicated to thesystem. The implant may include internal electronic componentsconfigured to automatically adjust the implant height and/or lordosisand deploy the retention spikes. One or more of these features may helpto minimize the size of the working corridor and minimize the number ofinstruments required to operate the implant.

According to one embodiment, an expandable implant includes upper andlower main endplates, an actuator assembly, and a sidecar assembly. Theupper and lower main endplates are configured to engage adjacentvertebrae. The actuator assembly is configured to cause an expansion inheight of the upper and lower main endplates. The sidecar assembly mayinclude a sidecar carrier, an upper carrier endplate pivotably coupledto an upper spike, and a lower carrier endplate pivotably coupled to alower spike. Forward translation of the sidecar carrier pushes againstthe upper and lower carrier endplates, thereby deploying the upper andlower spikes.

The expandable implant may include one or more of the followingfeatures. The upper carrier endplate may include a first tusk and thelower carrier endplate may include a second tusk. The first and secondtusks may extend toward a front of the implant. The first and secondtusks may be receivable in respective passageways in the upper and lowermain endplates to thereby guide translation of the upper and lowercarrier endplates. The first and second tusks may have a generallypolygonal cross-section that corresponds to the shape and dimensions ofthe respective passageway. The first and second tusks may allow fortranslation of the upper and lower carrier endplates with respect to themain endplates along a main longitudinal axis of the implant butrestricts all other translation and rotation. Each spike may extend froma proximal end coupled to the respective carrier endplate to a free end.The free end may be sharpened or pointed and configured to pierce bone.Each of the upper and lower main endplates may include a side extensionportion defining a side channel. The side channels may house and guidethe upper and lower spikes, respectively. Each spike may be connected tothe respective carrier endplate with a pin, thereby providing a hingedcoupling between the carrier endplate and the spike. When the carrierendplates move forward, the spikes may bottom out on the floor of thechannels, rotating about an axis of the pins connecting the spike to thecarrier endplate, and the spikes emerge from the top and bottom planesof the main endplates.

According to another embodiment, an expandable implant includes upperand lower endplates, an actuator assembly, a plurality of driving ramps,and a sidecar assembly. The upper and lower main endplates areconfigured to engage adjacent vertebrae. The actuator assembly includesa rotatable actuator having a shaft and a rotatable nut. The pluralityof driving ramps includes a front ramp, a mid-ramp, and a rear ramppositioned along the shaft of the actuator. The upper and lower mainendplates are engaged with the plurality of driving ramps. Rotation ofthe actuator and/or the nut causes movement of one or more of thedriving ramps, thereby causing an expansion in height of the upper andlower main endplates. The sidecar assembly includes a sidecar carrier,an upper carrier endplate pivotably coupled to an upper spike, and alower carrier endplate pivotably coupled to a lower spike. Forwardtranslation of the sidecar carrier pushes against the upper and lowercarrier endplates, thereby deploying the upper and lower spikes.

The expandable implant may include one or more of the followingfeatures. The rear ramp may include a bore for receiving the actuatorassembly and a pair of arms positioned on opposite sides of the bore.The rear ramp may include a dovetail slot along an outside face of onearm. The sidecar carrier may include a corresponding dovetail that mateswith the dovetail of the rear ramp, allowing the sidecar carrier totranslate with respect to the rear ramp along a main longitudinal axisof the implant while restricting all other translation or rotation. Thedovetail slot may decrease in height towards a back of the rear ramp.The rear ramp may include a retention tab configured to preventretraction of the spikes by preventing movement of the sidecar carrier.The retention tab may be defined by a relief cut such that the retentiontab protrudes outward from a side face of the rear ramp. When thesidecar carrier passes over the retention tab, the retention tab springsoutwardly to prevent the sidecar carrier from travelling backwards. Eachof the upper and lower main endplates may include a side extensionportion defining a side channel. The side channels may house and guidethe upper and lower spikes, respectively. When the sidecar carriertranslates forward, the carrier endplates move forward, the spikesbottom out on a floor of the channels, rotating and driving the spikesoutwardly from top and bottom planes of the main endplates.

According to another embodiment, an expandable implant includes upperand lower main endplates, an actuator assembly, and integrated retentionspikes. The upper and lower main endplates are configured to engageadjacent vertebrae. The actuator assembly includes a rotatable actuatorand a driving ramp positioned along the actuator configured to cause anexpansion in height of the upper and lower main endplates. Theintegrated retention spikes are deployable from the upper and lower mainendplates. The integrated retention spikes deploy when a sidecar carrieris translated forward, pushing against upper and lower carrier endplatesthat are pivotably coupled to the respective retention spikes. Anteriorand posterior heights of the implant may be independently adjustable forcontinuous adjustment of height and lordotic profile. The retentionspikes may maintain a constant penetration depth out of the upper andlower main endplates regardless of height or lordotic expansion.

According to another embodiment, an autonomous expandable implantincludes a computing unit, upper and lower main endplates, a pluralityof force sensors, an actuation assembly, a plurality of driving ramps,an electrical motor, and a power supply. The computing unit includes aprocessor with memory housed within the implant. The upper and lowermain endplates are configured to engage adjacent vertebrae. Theplurality of force sensors are housed in the upper and lower mainendplates. The force sensors are configured for load distributionmeasurement. The actuation assembly includes a rotatable actuator havinga shaft and a rotatable nut. The plurality of driving ramps arepositioned along the shaft of the actuator and engaged with the upperand lower main endplates. The electrical motor is configured to rotatethe actuator and/or the nut to move the driving ramps and expand theupper and lower main endplates. The power supply is configured forproviding power to the electrical motor.

The autonomous expandable implant may include one or more of thefollowing features. The implant may further include a sidecar assemblyincluding a sidecar carrier, an upper carrier endplate pivotably coupledto an upper spike, and a lower carrier endplate pivotably coupled to alower spike. Forward translation of the sidecar carrier pushes againstthe upper and lower carrier endplates, thereby deploying the upper andlower spikes. The implant may further include a linear motor configuredto translate the sidecar carrier, to thereby deploy the upper and lowerspikes. The computing unit may automatically inform the linear motor ofa drive initiation and duration to deploy the upper and lower spikes.The plurality of driving ramps may include a front ramp, a mid-ramp, anda rear ramp positioned along the shaft of the actuator. The implant mayfurther include a plurality of hall effect sensors located in the frontand mid ramps configured to provide real time positional information ofthe implant to a robotic navigation system. The computing unit mayautomatically inform the electrical motors of a drive amount andduration to adjust the height and lordosis of the implant based oninformation obtained from the force sensors. The implant may furtherinclude a wireless communication unit configured for sending andreceiving information to a robotic navigation system. The power supplymay include a wireless charging receiver, and an inserter instrument mayinclude a wireless charger configured to interface with the wirelesscharging receiver to power the implant.

According to another embodiment, an autonomous expandable implantincludes a front nose and a rear end including a housing, a computingunit, upper and lower main endplates, a plurality of force sensors, anactuator assembly, a plurality of driving ramps, a pair of electricalmotors, a sidecar assembly, a linear motor, and a power supply. Thecomputing unit includes a processor with memory located within thehousing. The upper and lower main endplates are configured to engageadjacent vertebrae. The plurality of force sensors are housed in theupper and lower main endplates. The force sensors are configured forload distribution measurement. The actuator assembly includes arotatable actuator having a shaft and a rotatable nut. The plurality ofdriving ramps includes a front ramp, a mid-ramp, and a rear ramppositioned along the shaft of the actuator and engaged with the upperand lower main endplates. The pair of electrical motors are configuredto independently rotate the actuator and the nut to move the drivingramps and expand the upper and lower main endplates. The sidecarassembly includes a sidecar carrier, an upper carrier endplate pivotablycoupled to an upper spike, and a lower carrier endplate pivotablycoupled to a lower spike. The linear motor is configured to translatethe sidecar carrier, to thereby deploy the upper and lower spikes. Thepower supply is configured for providing power to the motors locatedwithin the implant.

The autonomous expandable implant may include one or more of thefollowing features. The linear motor may be located behind the sidecarcarrier in the housing. The implant may further include a plurality ofhall effect sensors configured to provide real time positionalinformation of the implant to a robotic navigation system. The halleffect sensors may be located in the front and mid ramps. The computingunit may be located in the rear ramp. The implant may further include awireless communication unit located within the housing. The wirelesscommunication unit may be configured for sending and receivinginformation to a robotic navigation system.

According to yet another embodiment, a system of autonomouslycontrolling an expandable implant includes a robotic navigation systemand an inserter. The expandable implant may include a computing unit,upper and lower main endplates, a plurality of force sensors, anactuator assembly, a plurality of driving ramps, an electrical motor, asidecar assembly, a linear motor, and a power supply. The computing unitincludes a processor with memory housed within the implant. The upperand lower main endplates are configured to engage adjacent vertebrae.The plurality of force sensors are housed in the upper and lower mainendplates. The force sensors are configured for load distributionmeasurement. The actuator assembly includes a rotatable actuator havinga shaft and a rotatable nut configured to cause an expansion in heightof the upper and lower main endplates. The plurality of driving rampsare positioned along the shaft of the actuator and engaged with theupper and lower main endplates. The electrical motor is configured torotate the actuator and/or the nut to move the driving ramps and expandthe upper and lower main endplates. The sidecar assembly includes asidecar carrier, an upper carrier endplate pivotably coupled to an upperspike, and a lower carrier endplate pivotably coupled to a lower spike.The linear motor is configured to move the sidecar carrier, to therebydeploy the upper and lower spikes. The power supply is configured forproviding power to the motors. The robotic navigation system includes amoveable end effector and a display. The inserter is positionable in theend effector and configured to hold the expandable implant. The roboticnavigation system may include a wireless receiver for receiving implantforce and position information and a wireless transmitter fortransmitting user input to the implant. The inserter may include anelectromagnet and a wireless charger. The power supply may include awireless charging receiver, and the wireless charger of the inserter mayinterface with the wireless charging receiver to power the implant. Theelectromagnet on the inserter may generate an electric field causing thehall effect sensors to detect the relative location of the drivingramps.

According to yet another embodiment, a method of adjusting the heightand/or lordosis of an expandable implant and deploying integralretention spikes may include one or more of the following steps in anysuitable order: (1) preparing an intervertebral disc space, for example,including a discectomy; (2) inserting an endoscopic tube into the discspace; (3) introducing the expandable implant through the tube and intothe disc space in a collapsed configuration and seating it in anappropriate position in the intervertebral disc space; (4) deploying theretention spikes by translating the sidecar carrier toward the front endof the implant, thereby deploying the spikes; (5) expanding the implantin height and/or lordosis into the expanded position before or afterdeploying the spikes. In the case of an autonomous implant, the methodmay also include: (6) obtaining load distribution information from theforce sensors in the endplates; (7) applying a magnetic field to thehall effect sensors in the mid and front ramps with an electromagnet,for example, on an inserter to determine the physical position of theendplates and implant; (8) powering a wireless charging receiver in theimplant using a wireless charger, for example, on the inserter; (9)expanding the implant in height and/or adjusting lordosis usinginformation from a computing unit in the implant and/or arobotic/navigation system to operate DC motors in the implant to driveinternal actuators in the implant; (10) deploying the retention spikesby using information from a computing unit in the implant and/or arobotic/navigation system to operate a linear servo motor in the implantto move the sidecar carrier and deploy the spikes.

According to another embodiment, an expandable implant includes upperand lower main endplates configured to engage adjacent vertebrae, anactuator assembly, and a sidecar assembly. At least one of the upper andlower main endplates defines a curved channel and a straight channel.The actuator assembly is configured to cause an expansion in height ofthe upper and lower main endplates. The sidecar assembly includes asidecar carrier and a carrier endplate with a pusher engaged with aspike. The spike is positionable through the curved channel and thepusher is receivable in the straight channel. Forward translation of thesidecar carrier is configured to deploy the spike.

The expandable implant may include one or more of the followingfeatures. The curved and straight channels may overlap such that thecurved channel intersects the straight channel. The straight channel maybe a blind channel that extends along a longitudinal axis of theimplant, and the curved channel may arc outwardly toward an outersurface of the upper or lower main endplate. In a retracted position,the spike may be retained inside the curved channel, and as the sidecarcarrier translates forward, the spike travels through and extends fromthe curved channel, and the pusher follows the straight channel. Thespike extends from a proximal end to a free end, and a moveable jointmay connect the proximal end of the spike to a distal end of the pusher.The moveable joint may be a pivotable joint such that the proximal endof the spike includes a convex base receivable in a corresponding pocketin the pusher, and the pocket permits the convex base to travel along avertical axis to deploy the spike. The moveable joint may be a ball(e.g., a partial or full sphere) and socket joint.

According to yet another embodiment, an expandable implant includesupper and lower main endplates configured to engage adjacent vertebrae,an actuator assembly configured to cause an expansion in height of theupper and lower main endplates, and a sidecar assembly including asidecar carrier and a carrier endplate with a pusher engaged with aspike. The spike includes a convex base captured in a pocket defined ina free end of the pusher. Forward translation of the sidecar carrier isconfigured to translate the carrier endplate and deploy the spike.

The expandable implant may include one or more of the followingfeatures. The pocket may allow the convex base to travel up and downalong a vertical axis as the spike is pushed forward, rotating, andtranslating to a deployed position. The pocket may allow the spike torotate about an axis coincident with a radius of curvature of the spike.The convex base may be rounded but non-spherical. A bottom surface ofthe spike may define a slot, which causes the convex base to form adownward hook. The pocket may be undercut such that a tip of the pusherforms an upward hook. The upward hook of the pusher may be receivable inthe slot of the spike and the downward hook of the convex base may bereceivable in the pocket of the pusher. The actuator assembly mayinclude a rear ramp with a pair of parallel dovetail slots, and thesidecar carrier may include corresponding dovetails that mate with thedovetail slots of the rear ramp, allowing the sidecar carrier totranslate with respect to the rear ramp along a main longitudinal axisof the implant while restricting all other translation or rotation.

According to another embodiment, a method of installing an expandableimplant may include one or more of the following steps in any suitableorder: (1) inserting an expandable implant in a disc space betweenadjacent vertebrae, the implant having upper and lower main endplates,integrated retention spikes deployable from the upper and lower mainendplates, and a sidecar carrier assembly having a translatable sidecarcarrier for deploying the integrated retention spikes; (2) moving anactuator assembly in the expandable implant to cause an expansion inheight of the upper and lower main endplates; and (3) deploying theintegrated retention spikes by translating the sidecar carrier, therebyextending the retention spikes from the upper and lower endplates. Theretention spikes may be curved along their lengths with a degree ofcurvature, and the spikes may rotate about their own center ofcurvature. The retention spikes may be permitted to travel up and downalong a vertical axis only. The retention spikes may maintain a constantpenetration depth out of the upper and lower main endplates regardlessof height or lordotic expansion.

Also provided are kits including expandable fusion devices of varyingtypes and sizes, rods, fasteners or anchors, k-wires, inserters andother tools and instruments, robotic and/or navigation systems, andother components.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of an expandable interbody implant in anexpanded, lordotic position with integrated deployable retention spikesfully deployed according to one embodiment;

FIG. 2 is a top-down view of the expandable interbody implant with thesidecar carrier assembly omitted for clarity;

FIG. 3 is a rear view of the expandable interbody implant with thesidecar carrier assembly omitted for clarity;

FIG. 4 is an exploded view of the expandable interbody implant;

FIG. 5 is a perspective view of an upper main endplate according to oneembodiment;

FIG. 6 is a cross-sectional view of the upper endplate of FIG. 5 ;

FIG. 7 is a perspective view of a sidecar carrier endplate and tusk fordeploying the retention spike according to one embodiment;

FIG. 8 is a perspective view of the rear ramp with dovetail andretention tab according to one embodiment;

FIG. 9 is a cross-sectional view of the implant in a collapsed positionwith the integrated retention spikes contracted into the body of theimplant;

FIG. 10 is a cross-sectional view of the implant in the collapsedposition with the retention spikes deployed;

FIG. 11 shows a side view of implant in the collapsed position with theretention spikes contracted inside the body of the implant;

FIG. 12 shows a side view of the implant in the collapsed position withthe retention spikes deployed;

FIG. 13 shows a side view of the implant expanded in a parallelconfiguration with the retention spikes deployed;

FIG. 14 shows a side view of the implant fully expanded in height withlordotic expansion and the retention spikes deployed;

FIG. 15 shows a perspective view of the implant expanded in parallelwith the retention spikes deployed and a housing for internal electricalcomponents according to one embodiment;

FIG. 16 shows a side view of the implant illustrating electroniccomponent housing locations according to one embodiment;

FIG. 17 shows a top view of the implant illustrating electroniccomponent housing locations according to one embodiment;

FIG. 18 is a system flowchart depicting the electrical and mechanicalcomponents of the implant, a robotic/navigation system interface, and aninserter interface according to one embodiment;

FIG. 19 shows an exploded view of an expandable interbody implant withintegrated deployable retention spikes according to one embodiment;

FIG. 20 shows a cross-sectional view of the expandable implant of FIG.19 in a fully collapsed position with the integrated retention spikescontracted into the body of the implant;

FIG. 21 shows a cross-sectional view of the expandable implant of FIG.19 in the collapsed position with the retention spikes deployed;

FIGS. 22A-22B show top and side views, respectively, of the retentionspike retained to the carrier endplate via a pocket on a distal end of apusher according to one embodiment;

FIGS. 23A-23B show top and side views, respectively, of the retentionspike retained in the carrier endplate pusher via a full sphere retainedin a pocket according to an alternative embodiment;

FIGS. 24A-24B show top and side views, respectively, of the retentionspike retained in the carrier endplate pusher via a partial sphereretained in a pocket according to another embodiment;

FIGS. 25A-25B show front and rear perspective views of the sidecarcarrier slidably engaged with the rear ramp according to one embodiment

FIG. 26 is a cross-sectional view of the main upper endplate showing twooverlapping channels: a curved channel for accepting the retention spikeand a straight channel for accepting the pusher of the carrier endplateaccording to one embodiment;

FIG. 27 shows a close-up cross-sectional view of the retention spikesand carrier endplate pushers in a retracted position with the spikesfully retained in the curved channels; and

FIG. 28 shows a close-up cross-sectional view of the retention spikesand carrier endplate pushers in the deployed position with the spikesextending outward from the curved channels.

DETAILED DESCRIPTION

Embodiments of the disclosure are generally directed to expandableinterbody devices, systems, and methods. Specifically, embodiments aredirected to expandable interbody implants having integrated retentionspikes configured to deploy from the implant body to resist expulsion ofthe implant from the disc space. The expandable interbody implants maybe configured to communicate implant information with a robotic and/ornavigation system. For example, position and orientation of the implantmay be communicated as the implant expands. In addition, the implant maybe configured to automatically adjust its height and lordosis and deploythe retention spikes with internal electronic components. These featuresmay minimize the size of the working corridor and minimize the number ofinstruments required to operate the implant. The terms implant,interbody, interbody implant, fusion device, spacer, and expandabledevice may be used interchangeably herein.

Referring now to FIGS. 1-14 , an expandable interbody implant 10 isshown according to one embodiment. The expandable interbody implant 10includes an expandable interbody spacer with integrated deployableretention spikes 16, 18. The expandable implant 10 may include a firstmain or upper endplate 12, a second main or lower endplate 14, a firstor upper deployable spike 16, and a second or lower deployable spike 18.The upper and lower spikes 16, 18 are configured to be deployed by asidecar assembly 32, which may include a sidecar carrier 34 configuredto move an upper carrier endplate 36 coupled to upper anchor or spike 38and a lower carrier endplate 40 coupled to lower anchor or spike 42. Themain upper and lower endplates 12, 14 and upper and lower carrierendplates 36, 40 are configured to be expanded by an actuator assembly20, which may include a front ramp 22, a middle ramp 24, and a rear ramp26 moveable via an actuator or central drive screw 28 and an outer drivescrew or nut 30.

The anterior and posterior heights of the implant 10 may beindependently adjustable for continuous adjustment of height andlordotic profile. The retention spikes 16, 18 maintain constantpenetration depth out of the implant endplates 12, 14 regardless ofheight or lordotic expansion. The retention spikes 16, 18 may bedeployed prior to implant expansion by pushing sidecar carrier 34forward, driving the spikes 16, 18 through channel 110 in the mainimplant endplates 12, 14. When the sidecar carrier 34 is advanced to itsfinal forward position, a retention tab 132 un-depresses, locking thecarrier 34 in the forward position. The carrier endplates 36, 40 engagewith the main endplates 12, 14 and follow their movement through heightand lordotic expansion.

The implant 10 has a nose or front end 46 configured to be insertedfirst into a disc space between adjacent vertebral bodies and a back orrear end 48 configured to be coupled to an instrument for insertionand/or actuation of the actuator assembly 20. In one embodiment, theexpandable implant 10 is configured to be placed down an endoscopic tubeduring a minimally invasive surgical (MIS) procedure and into the discspace. The expandable implant 10 may be inserted in a collapsed orcontracted position and subsequently expanded in height and/or lordosis.The anchors or spikes 38, 42 may be deployed into the adjacent vertebralbodies to provide stability and prevent expulsion from the disc space.

The expandable fusion device 10 and components thereof may bemanufactured from a number of biocompatible materials including, but notlimited to: titanium, stainless steel, titanium alloys, non-titaniummetallic alloys, polymeric materials, plastics, plastic composites,PEEK, ceramic, and elastic materials.

The main upper and lower endplates 12, 14 and upper and lower carrierendplates 36, 40 are configured to engage with adjacent vertebrae. Asbest seen in FIG. 1 , the upper endplate 12 and upper carrier endplate36 are nested together to form an entire upper endplate of the device10. Similarly, the lower endplate 14 and lower carrier endplate 40 arenested together to form an entire lower endplate of the device 10. Asbest seen in FIG. 11 , the upper endplates 12, 36 and lower endplates14, 40 are also configured to nest or intermesh together in thecollapsed position such that the overall height of the implant isminimized in the collapsed position. The upper endplate 12 and uppercarrier endplate 36 will be described in further detail although it willbe understood that the description applies equally to the lower endplate12 and lower carrier endplate 40.

The upper endplate 12 may include an upper or outer surface 50configured to contact bone and a lower or inner surface 52 opposite tothe outer surface 50. The outer surface 50 may include a plurality ofteeth, ridges, gripping or purchasing projections, keels or othertexturing or friction increasing elements to aid in gripping theadjacent vertebral bodies. The inner surface 52 may define one or moreramps 54 configured to slidable interface with one or more correspondingramps 84, 86, 88 on the front ramp 22, mid ramp 24, and/or rear ramp 26,thereby providing for expansion in height of the endplates 12, 14. Theendplate 12 may define a through opening 56 extending between the outerand inner surfaces 50, 52 or a portion thereof. The through opening 56may be configured to receive bone graft or similar bone growth inducingmaterial to further promote and facilitate the intervertebral fusion.

As best seen in FIG. 2 , which omits the sidecar carrier assembly 32 forclarity, the endplate 12 defines an extension portion 90 near the frontend 46 of the endplate 12. The extension portion 90 is a sideprojection, which protrudes outwardly on one side of the endplate 12,thereby widening the footprint of the device 10. The extension portion90 defines a recessed area 92 on the side of the device 10 near the rearend 48. The recessed area 92 is sized and dimensioned to receive thebody of the upper carrier endplate 36. Although a right-side extensionportion 90 and recess 92 is shown for accommodating the upper carrierendplate 36, it will be appreciated that the extension 90 and recess 92could be provided on the opposite side.

As best seen in FIG. 7 , the upper carrier endplate 36 includes a bodywith an upper or outer surface 94 configured to contact bone and a loweror inner surface 96 opposite to the outer surface 94. The outer surface94 may include one or more teeth, ridges, gripping or purchasingprojections, keels or other texturing or friction increasing elements toaid in gripping the adjacent vertebral bodies. The inner surface 96 maydefine one or more ramps 98 configured to slidable interface with one ormore corresponding ramps 86, 100 on the middle ramp 24 and/or thesidecar carrier 34, thereby providing for expansion in height of thecarrier endplates 36, 40 in tandem with the upper and lower mainendplate 12, 14.

With further emphasis on FIG. 4 , the upper and lower endplates 12, 14and upper and lower carrier endplates 36, 40 are configured to beexpanded by an actuator assembly 20, which is configured to move aplurality of driving ramps 22, 24, 26 to expand the endplates 12, 14 andupper and lower carrier endplates 36, 40 in height. The actuatorassembly 20 may include a front ramp 22, a middle ramp 24, and a rearramp 26 moveable via an actuator or central drive screw 28 and an outerdrive screw or nut 30. The front ramp 22 may include a centrallongitudinal bore 58, the mid-ramp 24 may include a central longitudinalbore 60, and the rear ramp 26 may include a central longitudinal bore62. The plurality of driving ramps 22, 24, 26 may be positioned alongthe length of the actuator 28 and are configured to engage and drive theupper and lower endplates 12, 14, respectively. When one or more of thedriving ramps 22, 24, 26 are moved, they slide against the upper andlower endplates 12, 14 and/or upper and lower carrier endplates 36, 40,thereby providing for expansion in height. The expansion may include theability to individually adjust the anterior and/or posterior heights ofthe endplates 12, 14.

The implant 10 includes an expansion assembly 20. The expansion platformincludes two main endplates 12, 14, both interlocking symmetrically withrear, middle, and front ramps 22, 24, 26, which are aligned coaxiallyalong the central drive screw 28 such that the front ramp 22 is fixedtranslationally along the axis of the central drive screw 28 via thefront locking nut 77 and front bushing 102. The rear and middle ramps24, 26 are free to translate along the axis of the central drive screw28, the middle ramp 24 being driven by rotation of the central drivescrew 28. The central drive screw 28 is located concentrically withinthe outer drive screw 30, is free to translate along the axis of theouter drive screw 30, and may be driven by the outer drive screw 30. Theouter drive screw 30 is seated within the axial hole 62 in the rear ramp26, and is translationally fixed with respect to the rear ramp 26 viathe rear locking nut 104. Bushings 106 may act as bearing surfaces forthe rotational motion. The relative motion of the front and middle ramps22, 24 may cause the main endplates 12, 14 to expand and contract suchthat the anterior and posterior heights change at the same rate. Therelative motion of the front and rear ramps 22, 26 may cause the mainendplates 12, 14 to expand such that the posterior height decreases andthe anterior height increases.

The actuation assembly 20 is configured to independently expand therespective heights of the endplates 12, 14 and associated upper andlower carrier endplates 36, 40. The actuation assembly 20 includesrotatable actuator or central drive screw 28 and rotatable nut or outerdrive screw 30 configured to move the plurality of internal ramps 22,24, 26. The three driving ramps: front ramp 22, mid-ramp 24, and rearramp 26 interface with the actuator 28. The actuator 28 may include ashaft 64 extending from a proximal end 66 to a distal end 68. The shaft64 may include a first threaded portion 70, a second threaded portion72, and a non-threaded portion 74. The second threaded portion 72 may bepositioned between the first threaded portion 70 and the non-threadedportion 74. The threaded portions 70, 72 may have the same or differentattributes including outer diameters, handedness, thread form, threadangle, lead, pitch, etc.

The front driving ramp 22 includes through bore 58, and the frontdriving ramp 22 is positioned on the non-threaded portion 74 of theactuator 28. The mid-ramp 24 includes a threaded bore 60, and themid-ramp 24 is positioned on the second threaded portion 72 of theactuator 28. The mid-ramp 24 is threadedly moveable along the length ofthe second threaded portion 72 of the actuator 28. The rear ramp 26 isengaged with the nut 30, which is positioned along the first threadedportion 70 of the actuator 28 and is moveable along the length of thefirst threaded portion 70. The middle and rear driving ramps 24, 26 areeach moveable along their respective threaded portions 72, 70 to movethe upper and lower endplates 12, 14 and/or upper and lower carrierendplates 36, 40, and thereby expand the implant 10 in height. Thethreaded portions 70, 72 and non-threaded portion 74 may have the sameor different outer diameters. The threaded portions 70, 72 may have thesame or different threaded attributes or handedness. The proximal end 66of the actuator shaft 64 may include a first instrument retention recess76, for example, with a slotted head. The instrument recess 76 mayinclude one or more alternating fingers and slots, ribs, knurled grips,or other suitable engagement surfaces, which are configured to interfacewith a driver instrument to thereby rotate the actuator shaft 28. Thedistal end 68 of the actuator shaft 28 may be externally threaded toreceive internally threaded locking nut 77 configured to secure thefront ramp 22 to the actuator 28.

The actuation assembly 20 may include rotatable nut or outer drive screw30. The rotatable nut 30 may be configured to move the rear ramp 26independent of the mid-ramp 24 and front ramp 22. The nut 30 may extendfrom a proximal end 78 to a distal end 80. The proximal end 78 mayinclude a second instrument retention feature, such as a slotted head82. The slotted head 82 may include fingers and slots or other suitableengagement surfaces configured to interface with a driver instrument tothereby rotate the nut 30. The distal end 80 may be externally threadedto mate with internally threaded rear locking nut 104. When only the nut30 is rotated, the rear ramp 26 may be translated forward such that theposterior height increases. When the nut 30 remains stationary and onlythe actuator 28 is rotated, the rear ramp 26 and the mid-ramp 24 mayboth move backward such that the anterior height increases. When boththe actuator 28 and the nut 30 are rotated at the same time mid-ramp 24may move backward, thereby moving the endplates 12, 14 in parallel. Itwill be appreciated that the movement of the driving ramps 22, 24, 26and resulting expansion may be operated by the actuator 28 and/or nut 30with any suitable configurations and mechanisms.

The driving ramps 22, 24, 26 engage with upper and lower endplates 12,14 and associated upper and lower carrier endplates 36, 40 to therebymove the upper and lower endplates 12, 14 and upper and lower carrierendplates 36, 40 outwardly in height and/or lordosis.

As best seen in FIGS. 5 and 7 , the upper endplate 12 includes innersurface 52 configured to mate with the driving ramps 22, 26 and theupper carrier endplate 36 includes inner surface 96 configured to matewith driving ramp 24. The inner surfaces 52, 96 may include one or moreramped surfaces 54, 98. For example, the upper endplate 12 may includeat least one first ramped surface 54 near the front 46 of the device 10,at least one second ramped surface 54 near the rear 48 of the device 10,and at least one third ramped surface 54 between the first and secondramped surfaces 54. For example, the endplate 12, 14 may include a pairof first ramped surfaces 54, a pair of second ramped surfaces 54, and apair of third ramped surfaces 54 oriented to engage the respective ramps22, 24, 26.

The upper carrier endplate 36 may include at least one first rampedsurface 98 facing the front 46 of the device 10 and at least one secondramped surface 98 facing the rear 48 of the device 10. The sidecarcarrier 34 includes at least one ramped surface 100. For example, anoutside face of the sidecar carrier 34 may define a first upper rampedsurface 100 and a second lower ramped surface facing toward the front 46of the implant 10. The sidecar carrier 34 may include a ramp geometrythat mimics that of the rear ramp 26. In one embodiment, the firstramped surfaces 98 of the upper carrier endplate 36 facing the front 46of the device 10 may be configured to slidably interface with the ramps86 of the mid driving ramp 24. The second ramped surfaces 98 facing therear 48 of the device 10 may be configured to slidably interface withthe ramps 100 of the sidecar carrier 34. In this manner, the upperendplate 12 and the upper carrier endplate 36 may act as one unit duringexpansion, thereby engaging with the adjacent vertebral body.

The ramped surfaces 54, 98 may be angled continuous surfaces with agiven angle of slope. It is contemplated that the slope of the rampedsurfaces 54, 98 may be equal or can differ from each other. The rampedsurfaces 54, 98 may be generally straight ramped surfaces or may becurved ramped surfaces. The ramped surfaces 54, 98 may include maleslide ramps or protruding ramps. The ramped surfaces 54, 98 may bespaced apart at an equal distance such that the ramped surfaces aresubstantially parallel to one another. Although a specific arrangementof ramped surfaces is shown, it is envisioned that the number, location,and configuration of ramped surfaces may be modified or selected by oneskilled in the art.

The driving ramps 22, 24, 26 may include one or more ramped surfaces 84,86, 88. The ramped surfaces 84, 86, 88 of the driving ramps 22, 24, 26may be configured and dimensioned to engage the corresponding rampedsurfaces 54, 98 of the upper and lower endplates 12, 14 and upper andlower carrier endplates 36, 40, respectively. For example, the frontramp 22 may include one or more ramped surfaces 84, mid-ramp 24 mayinclude one or more ramped surfaces 86, and rear ramp 26 may include oneor more ramped surfaces 88. For example, the front ramp 22 may include afirst pair of upper ramped surfaces 84 and a second pair of lower rampedsurfaces 84. The mid-ramp 24 may include a first pair of upper rampedsurfaces 86 and a second pair of lower ramped surfaces 86. The rear ramp26 may include a first pair of upper ramped surfaces 88 and a secondpair of lower ramped surfaces 88. The ramped surfaces 84, 86, 88 may beangled continuous surfaces with a given angle of slope. It iscontemplated that the slope of the ramped surfaces 84, 86, 88 may beequal or can differ from each other.

The ramped surfaces 84, 86, 88 may be generally straight ramped surfacesor may be curved ramped surfaces. The ramped surfaces 84, 86, 88 mayinclude female slide ramps or recessed ramps configured to receive themale ramped surfaces 54, 98 of the upper and lower endplates 12, 14 andupper and lower carrier endplates 36, 40, respectively. A dovetail typeconnection may be formed between the ramped surfaces for stability andreliability, although other mating and sliding engagements can be used.It will be appreciated that the male and female ramps may be reversed ormay be otherwise configured to provide for slidable mating between theramps.

The front ramped surface(s) 54 of the endplate 12, 14 may be configuredto slidably interface with the ramped surface(s) 84 of the front drivingramp 22. The rear ramped surface(s) 54 of the endplate 12, 14 may beconfigured to slidably interface with the ramped surface(s) 88 of therear ramp 26. The middle ramped surface(s) 54 of the endplate 12, 14and/or ramped surface(s) 98 of the carrier endplate 36, 40 may beconfigured to slidably interface with the ramped surface(s) 86 of themid-ramp 24. As one or more of the driving ramps 22, 24, 26 moves, theramped surface or surfaces 84, 86, 88 pushes against the correspondingramped surface or surfaces 54, 98 of the upper and lower endplates 12,14 and upper and lower carrier endplates 36, 40. In this manner, theindividual driving ramps 22, 24, 26 control the rate of expansion of theupper and lower endplates 12, 14 and upper and lower carrier endplates36, 40. The upper and lower endplate 12, 14 and upper and lower carrierendplates 36, 40 are pushed outwardly into one of the expandedconfigurations.

With further emphasis on FIGS. 11-14 , the implant 10 has aspike-deployment assembly 32 configured to deploy upper and lower spikeassemblies 16, 18. The upper spike assembly 16 includes upper spike 38hingedly connected to upper carrier endplate 36 and lower spike assembly18 includes lower spike 42 hingedly connected to lower carrier endplate40. The spike-deployment assembly 32 may include sidecar carrier 34interlocked with the upper and lower carrier endplates 36, 40. Thepresence of retention spikes 38, 42 prevents expulsion to a higherdegree than a spacer with no expulsion-resistant features. Theintegration of retention spikes 38, 42 inside the implant 10 reduces thenumber of steps to deploy the spikes 38, 42 and allows for deploymentwith the same inserter used to place the spacer 10.

With further emphasis on FIGS. 5 and 6 , the spikes 38, 42 areconfigured to be deployed through the main endplates 12, 14. The mainendplates 12, 14 include an elongated side channel 110 that houses andguides the spikes 38, 42. Each endplate 12, 14 defines channel 110through the extension portion 90 of the endplate 12, 14 along the mainlongitudinal axis of the implant 10. The channel 110 is sized anddimensioned to house, guide, and deploy the respective spike 38, 42. Theextension portion 90 further defines passage 112 for receiving tusk 114of the carrier endplate 36, 40.

With further emphasis on FIG. 7 , each carrier endplate 36, 40 includesan elongate tusk 114 extending toward the front 46 of the implant 10.The tusk 114 may have a polygonal cross-section, for example, agenerally square or rectangular shape which corresponds to the shape anddimensions of the passage 112. The tusk 114 may be integral with thecarrier endplate 36, 40 or may be coupled thereto in a suitable manner.The top and bottom carrier endplates 34, 40 are constrained to the topand bottom main endplates 12, 14, respectively, via tusks 114 thatextend from the leading edge of the carrier endplates 36, 40 and insertsinto respective passageways 112 in the main endplates 12, 14. The tusk114 allows for translation of the carrier endplates 36, 40 with respectto the main endplates 12, 14 along the main longitudinal axis of thedevice 10, but restricts all other translation and rotation.

As shown in FIGS. 9 and 10 , each spike 38, 42 may be connected to therespective carrier endplate 36, 40 with a pin 116. The pin 116 may bereceivable through opening 118 in the carrier endplate 36, 40 to providea pivotable coupling between the endplate 36, 40 and the spike 38, 42.The anchor or spike 38, 42 may extend from a proximal end 120 coupled toendplate 36, 40 to a distal or free end 122. The free end 122 of thespike 38, 42 may have a pointed or sharp end 122 configured to piercebone. The spike 38, 42 may be curved or contoured along its body suchthat the spikes 38, 42 travel further outwardly as they are deployed.Although a curved spike is exemplified, the spike 38, 42 may include anysuitable anchor, shim, or fastener configured to resist expulsion of thedevice 10.

As the carrier endplates 36, 40 advance forward toward the mainendplates 12, 14, the tusks 114 travel through passages 112, and thespikes 38, 42 travel through the cut-out channels 110 in the mainendplates 12, 14. As the carrier endplates 36, 40 move forward, thespikes 38, 42 bottom out on the respective floors of the channels 110,rotating the spikes 38, 42 about the axis of the respective pins 116connecting the spike 38, 42 to the carrier endplate 36, 40. As best seenin FIG. 10 , the spikes 38, 42 emerge from the top and bottom planes ofthe main endplates 12, 14, thereby deploying the spikes 38, 42 outwardlyinto the adjacent vertebral bodies.

Although pins 116 are exemplified, it will be appreciated thatattachment and capture of the spikes 38, 42 may be achieved in a numberof ways. In the embodiment provided herein the spikes 38, 42 arecaptured by walls in the carrier endplates 36, 40 and pinned. Thisarrangement may also be achieved by incorporating a pin-like post offthe side of the spike itself, which may reduce the need for anadditional component. The attachment may also be accomplished by athreaded ball-and-socket interface that allows a threaded ball on theend of the spike to be threaded into an internally threaded sphericalsocket, for example.

With further emphasis on FIG. 8 , the rear ramp 26 may include adovetail 130 and retention tab 132 to direct and lock motion of thesidecar carrier 34. The rear ramp 26 may include a pair of arms 134about bore 62. An inner surface of each arm 134 may define a threadedportion, for example, configured to engage with an instrument. One arm134 of the rear ramp 26 may define the dovetail slot 130 along an outerside face of the ramp 26. The carrier 34 has a corresponding dovetailthat mates with the dovetail slot 130 of the rear ramp 26, allowing thecarrier 34 to translate with respect to the rear ramp 26 along the mainlongitudinal axis of the device 10 while restricting all othertranslation or rotation. The dovetail 130 may follow a path whose heightdecreases towards the rear of the rear ramp 26, such that the carrier 34is captured and unable to back all the way out of the ramp 26.

The retention tab 132 may act as an automatic lock to prevent retractionof the spikes 38, 42 after deployment. The retention tab 132 may beformed of relief cut that defines a polygonal tab, such as square orrectangular tab. The tab 132 may be configured to protrude outward, forexample, toward the front end 46 of the implant 10. In this manner, whenthe sidecar carrier 34 passes over the tab 132, the tab 132 springsoutwardly to prevent the sidecar carrier 34 from travelling back towardthe rear end 48 of the implant 10. When the spike-deployment assembly 32is fully retracted as best seen in FIG. 11 , the sidecar carrier 34blocks the retention tab 132 on the rear ramp 26. When thespike-deployment assembly 32 is fully advanced forward as best seen inFIG. 12 , the sidecar carrier 34 releases the retention tab 132 of therear ramp 26, which blocks the spike-deployment assembly 32 fromtranslating backward, thereby keeping the spikes 38, 42 deployed. Thepresence of the auto-lock retention tab 132 reduces the need for anadditional locking step to retain the spikes 38, 42.

In an exemplary embodiment, the full carrier assembly 32 isself-contained in the spacer body. In this manner, separate spikes orother anti-repulsion elements are not needed to secure the device 10.Although the dovetail 130 and retention tab 132 are exemplified herein,it will be appreciated that locking the spikes 38 in the deployedconfiguration may be achieved in a number of ways. For example, analternative way of achieving the same function may include positioningthe sidecar carrier 34 or the carrier endplate assembly 32 on theinserter. The inserter is then configured to push the auto-lockmechanism forward and retain the spikes 38, 42 directly.

With further emphasis on FIGS. 11-14 , a method of installing theexpandable fusion device 10 is shown according to one embodiment. Priorto insertion of the fusion device 10, the intervertebral space isprepared. An intradiscal osteotomy technique may include osteotomy ofthe posterior elements and ligamentum flavum, and opening a wide accessto underlying dural sac and the disc space. Osteotomes may be used toremove posterior osteophytes and the disc. In one method, a discectomyis performed where the intervertebral disc is removed in its entirety ora portion is removed. The endplates of the adjacent vertebral bodies maybe scraped to create an exposed end surface for facilitating bone growthacross the intervertebral space. The anterior longitudinal ligament(ALL) may be released via spreader or blunt dissection.

One or more endoscopic tubes may be inserted into the disc space. Asbest seen in FIG. 11 , one or more expandable fusion devices 10 may beintroduced into the intervertebral space in a collapsed configurationand seated in an appropriate position in the intervertebral disc space.The expandable implant 10 may be placed via a posterior lumbar interbodyfusion (PLIF) trajectory.

After the fusion device 10 has been inserted into the appropriateposition in the intervertebral disc space, the retention spikes 38, 42may be deployed as shown in FIG. 12 by translating the sidecar carrier34 toward the front end 46 of the implant 10. As the sidecar carrier 34translates forward, the upper and lower carrier endplates 36, 40translate forward as guided by the tusks 114. The spikes 38, 42, whichare pivotably connected to the carrier endplates 36, 40 translateforward and pivot outwardly into the deployed configuration.

The fusion device 10 may be expanded in height into the expandedposition before or after deploying the spikes 38, 42. As shown in FIG.13 , the endplates 12, 14, 36, 40 may be expanded in parallel. As shownin FIG. 14 , the endplates 12, 14, 36, 40 may be expanded in a lordoticconfiguration. The expandable spacer 10 provides for independentadjustable height and lordosis, which allows the user to fine-tune thefinal profile to meet the unique anatomy of the patient.

Rods may be reduced into screws placed prior to the osteotomy, and thescrews compressed. As the screws are brought closer together, thevertebral bodies may rock about the fulcrum created by the interbodyspacers, and segmental lordosis is increased, yielding the desiredcorrection.

Turning now to FIGS. 15-18 , expandable fusion device 10 is shownaccording to one embodiment with one or more electrical components 136for manipulating the implant 10 and/or communicating with a roboticsystem 138. Robotic and/or navigated assistance may be used to pre-planand increase accuracy/efficiency in the placement of the interbodyimplant and fixation. The orientation and position of the implant 10 inits final implanted position may be optimized with pre-op and intra-opscans utilizing robotic and/or navigational systems. Robotic and/ornavigation guidance may be used to correctly orient the implant andalign the implant for the desired expansion and deployment of theintegrated spikes 16, 18.

Robotic technology may use imaging taken prior to placement of aninterbody implant for initial registration. The procedure may rely ondirect visualization of motion markers to relay real-time position ofinstruments and devices, which is overlaid on the initial imaging. As aresult, once an interbody is placed, the expansion and resulting changein anatomy position may no longer be reflected on the navigationdisplay. Accordingly, there is a need for an implant that can relay itsposition and orientation to a computer in a way that does not requiredirect visualization. In addition, or alternatively, with a large numberof independently adjustable features and a small working corridor, thereis a need for a device that is autonomously adjustable without requiringdirect mechanical interaction with the implant 10.

According to one embodiment, the implant 10 is configured to communicateimplant position and orientation to the robot 138 before, during, andafter the implant 10 expands. FIG. 18 depicts one example of a systemflowchart showing implant 10 with embedded electrical components 136,inserter 150 with electromagnet 152 and wireless charger 154 configuredto install the implant 10, a robotic/navigation system 138 with awireless receiver 156 and a wireless transmitter 158 configured totransmit to and receive information from the implant 10, and themechanical components of the implant 10 including the drive screws 28,30, the retention spike carrier 34 for deploying spikes 38, 42, and thedriving ramps 22, 24 for adjusting the height and lordosis. It will beappreciated that the electrical components 136 in the implant 10 areelectrically coupled or connected to one another in a suitable manner totransfer energy, power, and/or information between the components.

The robotic and/or navigation system 138 may include a surgical robotsystem with an end-effector coupled to a moveable robot arm, a controldevice (for example, a computer having a processor and a memory coupledto the processor) for controlling the robot arm and end effector, and adisplay for receiving user inputs and displaying information to theuser. The end effector may be configured to hold and/or guide theinserter 150 during the operation. The robotic/navigation system 138includes wireless receiver 156 to receive information from the implant10, such as implant force and position information, and wirelesstransmitter 158 which transmits user input to the implant 10. Furtherdetails of robotic and/or navigational systems can be found, forexample, in U.S. Pat. Nos. 10,675,094, 9,782,229, and U.S. PatentPublication No. 2017/0239007, which are incorporated herein by referencein their entireties for all purposes.

According to one embodiment, the spacer 10 is capable of relaying itsposition to the robotic and/or navigation system 138, which overcomessignificant obstacles associated with pre-operative imaging whenregistration is lost after placement of the spacer 10. In addition, thespacer orientation, location, expansion, and/or deployment may betracked in real-time to better inform the navigated procedure followingspacer placement.

The implant 10 may include electrical components 136, such as sensors140, 146, a memory/storage/computing device 142, actuators 144, 162, apower supply 164, and wireless communication system 160, embedded invarious components throughout the spacer 10. The implant 10 may includean outer housing 135 configured to receive, for example, the computingunit 142, motors to actuate the drive screw 28, 30, wirelesscommunications unit 160, linear servo 162 to actuate the sidecar carrier34, and wireless charger 164 for providing power to the device 10.

The electronic components 136 may be responsible for up to three mainoperations: (1) measurement of force distribution across the implant 10;(2) subsequent adjustment of implant height and lordosis; and/or (3) themonitoring and communication of implant position and load. The endeffector of the robot 138 and/or a user may hold an inserter 150 forpositioning the implant 10. The wireless charger 154 in the inserter 150may be used to wirelessly provide power to the implant 10, and theelectromagnet 152 may be used to aid in the positional sensing by theimplant 10.

As best seen in FIGS. 16-17 , one or more force sensors 140 may becontained in or on the main endplates 12, 14. For example, the forcesensors 140 may be housed in the anterior and posterior portions of boththe top and bottom main endplates 12, 14. The force sensors 140 may beresponsible for load distribution measurement.

The computing unit 142 may be contained in the implant 10, for example,in the rear ramp 26. The computing unit 142 may include a processor orprocessing unit with memory, storage, and/or software. The computingunit 142 may be configured to monitor the relative forces over time tojudge load distribution. The computing unit 142 feeds this loaddistribution information through an algorithm to determine appropriateheight/lordosis change and rate of change.

Once the determination had been made, the computing unit 142 informs oneor more electrical motors 144 to adjust the height of the implant 10.For example, a pair of DC motors 144 may be provided in the housing 135behind the two drive screws 28, 30. The computing unit 142 may provideinformation including the drive amount and duration to the motors 144.The motors 144 are configured to automatically drive or rotate the twoscrews 28, 30 to provide the desired amount and type of expansion to theupper and lower endplates 12, 14.

The implant 10 may include one or more hall effect sensors 146. Forexample, the hall effect sensors 146 may be housed on or in the frontand mid ramps 22, 24, respectively. A separate electromagnet 152 may beprovided on the inserter instrument 150, for example. As theelectromagnet 152 generates a small magnetic field, the hall effectsensors 146 detect the relative location of the front and mid ramps 22,24 from the rear ramp 26, which is rigidly constrained to the inserter150. For any given relative position of the front, mid, and rear ramps22, 24, 26, there is a single known position and orientation of the mainendplates 12, 14. In this way, the location of the ramps 22, 24 as readfrom the hall effect sensors 146 yields enough information to projectreal-time implant position status. This information may be projected onthe display of the robotic/navigation system 138 after the sensorinformation is processed by the computing unit 142. The information maybe sent wirelessly through the wireless communication unit 160, alsoidentified as wireless transmitter and wireless receiver on the systemflowchart. The wireless communication unit 160 may be housed in the bodyof the rear ramp 26, for example.

When the user confirms final placement of the implant 10, a command isissued by the user and received by the wireless communication unit 160to initiate deployment. The computing unit 142 provides information tothe linear servo motor 162 including drive initiation and duration. Thelinear servo motor 162 may be housed behind the sidecar carrier 34,which pushes the carrier 34 forward, thereby deploying the retentionspikes 38, 42.

Throughout operation, the inserter 150 may include wireless charger 154on the end, which interfaces with receiving charger 164. The receivingcharger 164 may be housed in the rear ramp 26, for example, and providesa power supply for automatic operation of the implant 10. In thismanner, the spacer 10 is capable of autonomously driving itself, whichreduces the need for multiple drivers to drive anterior and posteriorheight, as well as anchor deployment. This simplifies operative workflowand increases efficiency of spacer placement. The reduction of multipleinstruments may also reduce the required working corridor, tissuedisruption, and improving patient recovery time.

Turning now to FIGS. 19-27 , expandable interbody implant 200 is shownaccording to another embodiment. Expandable implant 200, similar toimplant 10, includes integrated deployable retention spikes 16, 18 withsome modifications to the retention mechanism of the spikes, channelgeometry, spike motion path, and/or order of implant operations.

Implant 200 includes an expansion platform and a sidecar spikedeployment assembly. As best seen in FIG. 19 , the expansion platformmay include, similar to implant 10, upper and lower main endplates 12,14, two concentric drive screws 28, 30, two translating ramp components22, 24, two locking nuts 77, 104, and three PEEK washers 102, 106. Thethird rear ramp component 26 may serve as the connection between theexpansion platform and the spike deployment platform.

The spike deployment platform includes ramped sidecar carrier 34 whoseramps 100 connect to two carrier endplates 36, 40 that retain tworespective spikes 38, 42. The spikes 38, 42 and carrier endplates 36, 40translate in and out of channels 210, 212 in the two main upper andlower endplates 12, 14, which are linked to the expansion platform withinclined ramps 54. The top and bottom carrier endplates 34, 40 areconstrained to the top and bottom main endplates 12, 14, respectively,via the tusks or pushers 214 that extend from the leading edge of thecarrier endplates 36, 40 and insert into the respective passageways 212in the main endplates 12, 14. The pushers 214 allows for translation ofthe carrier endplates 36, 40 with respect to the main endplates 12, 14along the main longitudinal axis of the device 200, but restricts allother translation and rotation.

The movement of the expansion platform allows for expansion in heightand the spike deployment platform allows for deployment of the spikes16, 18. As best seen in FIG. 20 , the expandable implant 200 may beinserted in a collapsed and contracted position and subsequentlyexpanded in height and/or lordosis. The carrier endplates 36, 40 mayengage with the main endplates 12, 14 and follow their movement throughheight and lordotic expansion. As best seen in FIG. 21 , the anchors orspikes 38, 42 may be deployed into the adjacent vertebral bodies toprovide stability and prevent expulsion from the disc space. In thisembodiment, the user has the ability to deploy the spikes 38, 42 eitherbefore or after the implant 200 has been expanded in height/lordosis,which provides more flexibility in the order of implant operations andworkflow of the procedure.

In the embodiment previously described for implant 10, the retentionspikes 38, 42 are pinned to the carrier endplates 36, 40. The pinningcauses the spike 38, 42 to pivot about the axis of the pin 116 as thespike 38, 42 moves through its deployment motion path. This may resultin a windshield wiper motion path which may cause the implant to pullitself forward as the spikes 38, 42 are deployed and/or the spikes 38,42 may cut an arced recess into the vertebral endplates. Removing thepin as the retention and deployment mechanism for the spike 38, 42allows the spike 38, 42 to rotate about its own center of curvature,rather than rotating around the pin. This removes the windshield wipermotion during deployment, and keeps the spike's motion tangent to itsown shape, optimizing hold in bone and reducing the potential for voidsto be made during deployment.

In this embodiment for implant 200, the pin(s) may be replaced with analternative moveable joint. For example, as shown in FIGS. 22-24 , thejoint may include a pivot joint, hinge joint, saddle joint, ball andsocket joint, or other suitable joint for rotating, pivoting and/orextending the respective spikes 38, 42. Although the embodiments inFIGS. 22-24 are shown and described with respect to upper carrierendplate 36 and upper spike 38, it will be appreciated that thedescription applies equally to the lower carrier endplate 40 and lowerspike 42.

In one embodiment shown in FIGS. 22A-22B, the joint may include a pivotjoint with a convex base 202 on the proximal end 120 of the spike 38, 42captured in a corresponding pocket 218 on the distal end 216 of thecarrier endplate pusher 214. In this manner, the spike 38, 42 isretained in the carrier endplate pusher 214 via the convex base 202 andpocket 218 interface. The pocket 218 allows the convex base 202 totravel up and down along a vertical axis and the spike 38, 42 is pushedforward, rotating, and translating into its deployedposition/orientation. The pocket 218 on the pusher 214 may be undercutsuch that the undercut can pull on the front surface of the convex base202 to retract the spikes 38, 42 after deployment.

The anchor or spike 38, 42 may extend from a proximal end 120 engagedwith carrier endplate 36, 40 to a distal or free end 122. The proximalend 120 of the spike 38, 42 may include convex base 202, for example,having a generally convex outer shape. The convex outer shape of thebase 202 may be rounded but non-spherical. A bottom surface of the spike38, 42 may define an undercut or slot 204, which causes the convex base202 to overhang or form a downward hook at the end of the spike 38, 42.The slot 204 may have a smooth rounded surface. The opposite free end122 of the spike 38, 42 may have a pointed or sharp end 122 configuredto pierce bone. A top surface of the spike 38, 42 may define one or moregrooves or scoops 206 along its longitudinal length. For example, a pairof scoops 206 may be bifurcated by a rib extending centrallytherebetween. The spike 38, 42 may be curved or contoured along itsbody, with a given degree of curvature, such that the spikes 38, 42travel a curved path as they are deployed.

The carrier endplate 36, 40 includes an upper surface 94 for engagingthe adjacent vertebra (e.g., with teeth) and a lower surface 96 withramps 98 to slidably interface with one or more corresponding ramps 86,100 on the middle ramp 24 and/or the sidecar carrier 34, therebyproviding for expansion in height of the carrier endplates 36, 40 intandem with the upper and lower main endplates 12, 14. Similar to tusk114, each carrier endplate 36, 40 includes extension, rod, or pusher 214extending toward the front 46 of the implant 10. The pusher 214 may belarger in cross-section than tusk 114, and may have any suitablecross-section, for example, a cylindrical or polygonal shape whichcorresponds to the shape and dimensions of the straight passageway 212through the main endplate 12, 14. The pusher 214 may extendlongitudinally off the front of the carrier endplates 36, 40 and may beintegral with the carrier endplate 36, 40 or may be coupled thereto in asuitable manner.

As best seen in FIG. 22B, the pusher 214 terminates distally at a tip orfree end 216. A top portion of the pusher 214 defines pocket 218configured to receive corresponding convex base 202 of the spike 38, 42.The pocket 218 may be undercut such that the tip 216 defines an overhangor upward hook at the end of the pusher 214. In this manner, the upwardhook of the tip 216 is receivable in the slot 204 of spike 38, 42 andthe downward hook of base 202 is receivable in the pocket 218 of pusher214. The pocket 218 is shaped such that the convex base 202 is free tomove up and down along a vertical axis, but is still retained therein.This allows the spikes 38, 42 to rotate about an axis coincident withtheir own radius of curvature, thereby eliminating the windshield wipermotion.

Turning now to FIGS. 23A-23B, another embodiment is shown of a ball andsocket joint connecting the spike 38, 42 to the pusher 214. In thisembodiment, the convex base 202 is substituted with a ball 222 and thepocket 218 in the pusher 214 is substituted with a socket 224 sized andconfigured to receive the ball 222. The ball 222 may be a full spherereceivable in the socket 224. The sphere 222 may be partially truncatedon the top to minimize interference during rotation. The ball 222 may beseparated from the main body of the spike 38, 42 with a neck 226 havinga reduced diameter relative to the ball 222. The ball and socketcombination permits the spike 38, 42 to pivot about the joint, therebyallowing the spike 38, 42 to pivot and extend outward during deployment.

Turning now to FIGS. 24A-24B, another embodiment is shown of a partialsphere and socket joint connecting the spike 38, 42 to the pusher 214.Similar to the embodiment shown in FIGS. 23A-23B, the proximal end 120of the spike 38, 42 includes ball 222, which is receivable in socket 224at the distal end 216 of the pusher 214. In this embodiment, the ball222 may define a partial sphere and may include one or more ribsconfigured to retain the ball 222 and/or guide movement of the spike 38,42. The neck 226 may define a flat connecting the truncated top face ofthe ball 222 to the main body of the spike 38, 42. The partial ball andsocket combination permits the spike 38, 42 to pivot about the joint,thereby allowing the spike 38, 42 to pivot and extend outwardly duringdeployment.

Turning now to FIGS. 25A-25B, the sidecar assembly is moveable via theslidable interface with the rear driving ramp 26. Similar to implant 10,the rear ramp 26 may include one or more dovetails 230 and a retentiontab 232 to direct and lock motion of the sidecar carrier 34. In thisembodiment, the single dovetail 130 is replaced with a pair of paralleldovetails 230 positioned on opposite sides of the retention tab 232. Asbest seen in FIG. 25A, the slidable dovetails 230 may include a recessor mortise in the body of the rear ramp 26 and an extension or tenonextending from the sidecar carrier 34. The tenon may be flared orenlarged at the free end to resist separation of the components. It willbe appreciated that this configuration may be reversed, more or lessslidable dovetails may be used, or another interface may be used toallow for slidable engagement between the sidecar carrier 34 and therear ramp 26. The parallel dovetail slots 230 on the side of the rearramp 26 engage with corresponding dovetails on the sidecar carrier 34,allowing the sidecar carrier 34 to slide forward and backward. Thecarrier endplates 36, 40 have inclined ramps 98 that engage withreceiving ramps 100 on the sidecar carrier 34 such that the carrierendplates 36, 40 are towed forward and backward along with the sidecarcarrier 34, and are also allowed to move up and down along the ramps 98,100. The rear ramp 26 and/or the sidecar carrier 34 may include one ormore holder recesses 234 configured to connect with an inserter or otherinstrument (not shown).

With further emphasis on FIGS. 26-28 , the upper and lower endplates 12,14 each define a channel 210 for receiving the spike 38, 42 and achannel 212 for receiving the pusher 214. In implant 10, there were twoseparate channels 110, 112 in each endplate 12, 14: one accepted theguide tusk 114 from the carrier endplate 36, 40 and one guided theretention spike 38, 42 through its deployment path. In implant 200,these channels 210, 212 are coincident with one another. This allowsboth the pusher 214, retention spike 38, 42, and associated channels210, 212 to all be larger, and reduces the need for lateral nesting ofthese features. These changes may help with manufacturability andmechanical strength of the implant 200.

As best seen in FIG. 26 , spike channel 210 is a curved channelconfigured to retain and guide deployment of the spike 38, 42 and pusherchannel 212 is a straight channel configured to receive the distal end216 of the pusher 214 as the spikes 38, 42 are deployed. The straightchannel 212 may be a blind channel that extends generally along the mainlongitudinal axis of the implant 200 between the front and back of theendplate 12, 14. The curved channel 210 may arc outwardly toward theouter surface 50 of each endplate 12, 14. The curved channel 210 forspike 38, 42 and straight channel 212 for pusher 214 overlap such thatthese channels 210, 212 intersect with one another. Arranging the curvedchannel 210 and straight channel 212 so that they overlap allows bothchannels 210, 212 to be larger within the given envelope of the endplate12, 14, which increases the size and strength of the members 38, 42, 214that pass through them.

As best seen in FIG. 27 , in the retracted position, the spikes 38, 42are retained inside the curved channels 210 through the endplates 12,14. The pusher 214 both retains the spike 38, 42 and guides each carrierendplate 36, 40 in and out of the straight channel 212 on its associatedmain endplate 12, 14. As the sidecar carrier 34 and carrier endplateassembly is pushed forward, each spike 38, 42 is deployed through therespective curved channel 210 in the main endplate 12, 14. The pushers214 move forward and follow the straight channels 212. As best seen inFIG. 28 , in the deployed position, the spikes 38, 42 follow the curvedchannels 210 and extend outward from the main endplates 12, 14. Thespikes 38, 42 emerge from the top and bottom planes of the mainendplates 12, 14, thereby deploying the spikes 38, 42 outwardly into theadjacent vertebral bodies.

It will be further understood that various changes in the details,materials, and arrangements of the parts which have been described andillustrated in order to explain the nature of this invention may be madeby those skilled in the art without departing from the scope of theinvention as expressed in the claims. One skilled in the art willappreciate that the embodiments discussed above are non-limiting. Itwill also be appreciated that one or more features of one embodiment maybe partially or fully incorporated into one or more other embodimentsdescribed herein.

What is claimed is:
 1. An expandable implant comprising: upper and lowermain endplates configured to engage adjacent vertebrae, at least one ofthe upper and lower main endplates defines a curved channel and astraight channel; an actuator assembly configured to cause an expansionin height of the upper and lower main endplates; and a sidecar assemblyincluding a sidecar carrier and a carrier endplate with a pusher engagedwith a spike, wherein the spike is positionable through the curvedchannel and the pusher is receivable in the straight channel, andwherein forward translation of the sidecar carrier deploys the spike. 2.The expandable implant of claim 1, wherein the curved and straightchannels overlap such that the curved channel intersects the straightchannel.
 3. The expandable implant of claim 1, wherein the straightchannel is a blind channel that extends along a longitudinal axis of theimplant.
 4. The expandable implant of claim 1, wherein the curvedchannel arcs outwardly toward an outer surface of the upper or lowermain endplate.
 5. The expandable implant of claim 1, wherein in aretracted position, the spike is retained inside the curved channel, andas the sidecar carrier translates forward, the spike travels through andextends from the curved channel, and the pusher follows the straightchannel.
 6. The expandable implant of claim 1, wherein the spike extendsfrom a proximal end to a free end, and a moveable joint connects theproximal end of the spike to a distal end of the pusher.
 7. Theexpandable implant of claim 6, wherein the moveable joint is a pivotablejoint such that the proximal end of the spike includes a convex basereceivable in a corresponding pocket in the pusher, and the pocketpermits the convex base to travel along a vertical axis to deploy thespike.
 8. The expandable implant of claim 6, wherein the moveable jointis a ball and socket joint.
 9. An expandable implant comprising: upperand lower main endplates configured to engage adjacent vertebrae; anactuator assembly configured to cause an expansion in height of theupper and lower main endplates; a sidecar assembly including a sidecarcarrier and a carrier endplate with a pusher engaged with a spike,wherein the spike includes a convex base captured in a pocket defined ina free end of the pusher, and wherein forward translation of the sidecarcarrier, translates the carrier endplate and deploys the spike.
 10. Theexpandable implant of claim 9, wherein the pocket allows the convex baseto travel up and down along a vertical axis and the spike is pushedforward, rotating, and translating to a deployed position.
 11. Theexpandable implant of claim 10, wherein the pocket allows the spike torotate about an axis coincident with a radius of curvature of the spike.12. The expandable implant of claim 9, wherein the convex base isrounded but non-spherical.
 13. The expandable implant of claim 9,wherein a bottom surface of the spike defines a slot, which causes theconvex base to form a downward hook.
 14. The expandable implant of claim13, wherein the pocket is undercut such that a tip of the pusher formsan upward hook.
 15. The expandable implant of claim 14, wherein theupward hook of the pusher is receivable in the slot of the spike and thedownward hook of the convex base is receivable in the pocket of thepusher.
 16. The expandable implant of claim 9, wherein the actuatorassembly includes a rear ramp having a pair of parallel dovetail slots,and the sidecar carrier includes corresponding dovetails that mate withthe dovetail slots of the rear ramp, allowing the sidecar carrier totranslate with respect to the rear ramp along a main longitudinal axisof the implant while restricting all other translation or rotation. 17.A method of installing an expandable implant, the method comprising:inserting an expandable implant in a disc space between adjacentvertebrae, the implant having upper and lower main endplates, integratedretention spikes deployable from the upper and lower main endplates, anda sidecar carrier assembly having a translatable sidecar carrier fordeploying the integrated retention spikes; moving an actuator assemblyin the expandable implant to cause an expansion in height of the upperand lower main endplates; and deploying the integrated retention spikesby translating the sidecar carrier forward, thereby extending theretention spikes from the upper and lower endplates.
 18. The method ofclaim 17, where the retention spikes have a degree of curvature, and thespikes rotate about their own center of curvature.
 19. The method ofclaim 17, wherein the retention spikes are permitted to travel up anddown along a vertical axis only.
 20. The method of claim 17, wherein theretention spikes maintain a constant penetration depth out of the upperand lower main endplates regardless of height or lordotic expansion.